1. Aim. To teach:
a. the action of the firing mechanism; and b. how to fire the gun and the action on misfire.
2. Time. Two 40 minute lessons.
3. Method. A basic instructional lesson.
4. Stores:
a. 84mm complete 1 per 3 soldiers,
b. 84mm dummy rounds 2 per gun,
c. 84mm mechanism board 1 per class,
d. 84mm duplex ammunition container 1 set per gun, e. armour representative targets 1 per gun,
f. mechanism diagram 1 per gun,
5. Preparation. The instructor should:
a. lay out the section room;
b. fit the telescope to each gun;
c. position representative targets on the wall in front of the guns and one metre above floor level;
d. chamber test each dummy round; and
e. check that all front and rear end caps are removable.
6. Miscellaneous. Consider the following:
a. number the section in groups of three and allocate each group to a gun prior to safety precaution;
b. explain that during the practice stage when a number is called out, that man is to act as No. 1 on the gun and the second number called is to act as No. 2. Use the command "Change Around" and explain the system of rotation; and
c. during the practice stage of misfire and further action drills use the commands
"WEAPON FAILS TO FIRE, MISFIRE, PRIMER STRUCK, PRIMER NOT STRUCK, 60 SECONDS ARE UP".
CONDUCT OF THE LESSON 7. Safety Precautions. Normal.
8. Review. Loading and unloading.
9. Introduction. Explain that in battle the gun numbers must work as a team to load quickly and fire accurately. Any misfire must be dealt with quickly in order to prevent armour breaking through the defended position. A high standard of training in these skills is required of the team.
A knowledge of the firing mechanism will assist the team in determining the cause of the misfire and its remedy.
10. Basic Firing Mechanism.
a. When the gun is cocked the firing rod spring is compressed against the front end cap. The cocking rod notch on the cocking rod head engages with the hook on the sear.
b. When the trigger is pressed the sear is disengaged and the spring drives the firing rod to the rear.
c. The firing pin cam bears against the inner part of the firing pin, which is forced inwards on to the primer cap of the round.
d. The safety catch can only be applied when the cocking rod is forward in the cocked position.
Figure 2-4-1 Mechanism 11. Confirm by Questions.
12. Firing. Explain and demonstrate the following:
a. when the No. 1 decides or is ordered to engage the target he is to set the sights and put the safety catch to "FIRE";
b. when the hold and aim is correct the No. 1 orders "STAND BY", takes the first trigger pressure, fires and follows through as taught;
c. when the trigger has been operated the No. 1 is to open his left eye, observe the strike, immediately cock the gun, put the safety catch to "SAFE" and order
"LOAD";
d. on the order "STAND BY" the No. 2, having ensured that the backblast area is clear, is to face forward in order to reduce the likelihood of hearing damage. He is then to observe the target area and assist the No. 1 in observing the strike of the round. To reduce the amount of discomfort caused by the over pressure around the gun at the moment of firing he should stay midway between the muzzle and the breech;
e. after firing and on receiving the order "LOAD" from the No. 1 the No. 2 is to:
(1) repeat the order "LOAD" and open the breech;
(2) remove the empty case and throw it off to a flank well clear of the backblast area; and
(3) examine the chamber for unburnt propellant, remove it if necessary and load again as taught.
f. before firing again, the No. 1 is to make any corrections to range, lead or point of aim depending on the observation of strike of the previous round; and
g. should the backblast area not be clear at any time tile No. 2 is to call out "STOP".
13. Confirm by Practice.
14. Hangfire and Misfire. Explain that:
a. a hangfire is an abnormal time lag between the trigger being operated and the round being fired. As the delay is caused by slow burning propellant, the round could fire without warning and therefore the gun is to be kept pointed at the target while the correct drill is carried out; and
b. a misfire is caused by either a faulty firing mechanism or a faulty round.
15. Misfire Drills. Explain and demonstrate where necessary.
a. If the weapon fails to fire, the following actions shall be taken:
(1) No. 1 maintains his point of aim, recocks the weapon, puts the safety catch to "SAFE" and orders No. 2 to "CHECK VENTURI";
(2) No. 2 taps the venturi lock knob to the rear and reports to the No. 1
"VENTURI LOCK CHECKED"; and
(3) No. 1 places the safety catch to "FIRE" aims and carries out the proper firing drills.
b. If the weapon fails to fire a second time, the following action shall be taken:
(1) No. 1 will report "MISFIRE" and the No. 2 repeats "MISFIRE";
(2) Nos. 1 and 2 wait one minute with the No. 1 maintaining the aim in the event of a possible hangfire;
(3) if the gun has not fired after one minute, No. 1 recocks the weapon, places the safety catch to "SAFE" and orders "MISFIRE UNLOAD". No. 2
repeats "MISFIRE UNLOAD"; and
(4) after unloading the gun one of the following drills shall be carried out:
(a) Primer Struck. After removing the misfired round, No. 2 inspects the primer. If the primer is fully struck he reports "PRIMER STRUCK", No. 1 repeats "PRIMER STRUCK". The No. 2 then lays the misfired round aside for disposal. If the target is still in view the team reloads and carries on firing; or
(b) Mechanical Breakdown. If, on examination of the primer, No. 2 finds that it has been lightly struck or not struck at all he will report
"MECHANICAL BREAKDOWN". No. 2 will then close the venturi and report "GUN CLEAR". No. 1 repeats "GUN CLEAR"
and completes the unloading drill. The firing mechanism must then be stripped and damaged parts replaced.
16. Confirm by Practice.
17. Other Conditions. At night, if there is a misfire, the No. 1 is to carry out the same drill as in daylight. As it may not be possible to see if the primer cap has been struck the No. 2 is to unload and immediately load with another round. If that round is also a misfire the gun team is to unload and inspect the firing mechanism.
18. Confirm by Questions.
19. Conclusion.
a. Questions from the section on the entire lesson.
b. Confirm by questions and practice.
c. Safety precautions, normal.
20. Summary. To include the following:
a. the importance of practice is to promote good team work and instinctive handling;
b. the safety pause of one minute must be observed if a misfire occurs during training; and
c. a forecast of the section's next lesson in this subject.
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LESSON 5 - BORESIGHTING THE TELESCOPE AND IRON SIGHTS